Understanding Death and Decomposition: Forensic Insights

1. Death and Decomposition

2. What will we cover in this section? • Distinguish between the five manners of death: natural, accidental, homicidal, suicidal, undetermined • Use evidence or rigor, algor, and livor mortis to calculate the approximate time of death • Describe the stages of decomposition of a corpse • Explain how time of death can be estimated using insect evidence • Describe how various environmental factors may influence estimated time of death

3. Vocabulary • Algor mortis – The cooling of the body after death • Autolysis – The spontaneous break-down of cells as they self-digest • Cause of death – The immediate reaction for a person’s death (i.e. heart attack) • Death – The cessation, or end, of life • Decomposition – the process of rotting and breaking down

4. Vocabulary 6. Forensic Entomology – the study of insects as they pertain to legal issues • Livor Mortis – the pooling of blood in tissues after death resulting in a reddish color of the skin • Manner of Death – one of four means by which someone dies (natural, etc.) • Mechanism of Death – the specific body failure that leads to death • Rigor Mortis – the stiffening of skeletal muscles after death

5. Manner of Death • Natural – interruption and failure of body functions resulting from age or disease • i.e. – heart failure, cancer • Accidental – caused by unplanned events • i.e. – car accidents, falling from a ladder • Suicide – person purposefully kill oneself • i.e – hanging, drug overdose, gunshot • Homicide – death of one person caused by another person • Undetermined – listed as the official cause when cause cannot be determined

6. Manner of Death • A man with a heart condition is attacked and dies from a heart attack during the assault. • accident, natural or homicide? • An elderly woman dies after being kept from receiving proper health care by her son. • accident, natural, or homicide?

7. Manner of Death • In both cases it is…… HOMICIDE!!! • But, can you prove it in court????

8. Cause and Mechanism • Cause of Death – disease, injury, stroke, heart attack • Homicide – shooting, burning, drowning, strangulation, etc. • Mechanism of Death – specific change that brought about death • If cause is shooting – loss of blood, ceasing of brain function • If cause is heart attack – pulmonary arrest (stops beating)

9. Cause and Mechanism • “massive trauma to the body leading to pulmonary arrest” • Cause? • Mechanism?

10. Do you remember….? • How long after death does… • Livor mortis? • Rigor mortis? • Algor mortis? • It is ALWAYS important to record surrounding temps, environment, clothing, wind, sun, etc to use when calculating time of death!

11. Livor Mortis • Means “death color” • Begins two hours after death occurs • 2-8 hours after death – push area of body and color will disappear • More than 8 hours after death – color will remain • Temperature has an effect • Cooler temp – occurs slower • Warmer temp – occurs faster

12. Livor Mortis

13. Livor Mortis • Can tell you what position a body was in the first 8 hours after death • Blood pooled at face, chest – body face down • Blood pooled at back, buttocks, back of head – body face up • What if blood is pooled in lower legs and feet, lower arms and hands? • Can also tell if the body was moved • Dual lividity (pooling of blood) • Occurs if person left in killed position at least 2 hours and then moved before lividity is permanent • Very common in homicide victims

14. Rigor Mortis • Means “death stiffness” • Occurs because muscles unable to relax, they stay contracted • Caused by a build-up of calcium • Begins within 2 hours after death • Body is most rigid at about 12 hours after death and slowly declines to about 36 hours • Some variables may extend it past 36 hours up to 48 hours • Starts in the head and slowly works its way down to legs

16. Rigor Mortis

17. Factors that affect when rigor mortis sets in and how long it lasts • Ambient temp – • cooler the body, slower the onset • warmer the body, faster the onset • Person’s weight – • Body fat stores extra oxygen, will slow down onset • Type of clothing • Presence of clothing speeds onset • Naked bodies slow onset

18. Factors that affect when rigor mortis sets in and how long it lasts • Illness – • Fever – • Hypothermia – • Level of physical activity shortly before death • Exercise or struggling will increase onset rate • Sun exposure • Direct sunlight makes body warmer – increases onset rate

19. Algor Mortis • Means “death heat” • Thermometer inserted into liver as standard • Timeline: • 0-12 hours after death: 1.4°F per hour • > 12 hours after death: 0.7° F per hour until reaching surrounding temp • Factors affecting heat loss: • Cooler environment – loses heat faster • More body fat, clothing – loses heat slower

20. Other Factors also Used for Time of Death • Stomach Contents • Potassium present ocular fluid

21. Stages of Decomposition • Within two days after death: Initial Decay • Cell autolysis begins. • Green and purplish staining occurs from blood decomposition. • Skin takes on a marbled appearance. • Face becomes discolored. • After four days: Putrefaction • Skin blisters. • Abdomen swells with carbon dioxide (released by bacteria living in the intestines).

22. Stages of Decomposition • Within six to ten days: Putrefaction • Corpse continues to bloat with CO2 as bacteria continue to feed on tissues • Eventually, gas causes chest and abdominal cavities to burst and collapse. • Fluids begin to leak from body openings as cell membranes rupture • Eyeballs and other tissues liquify • Skin Sloughs off

23. Stages of Decomposition Named! • Initial Decay –0-3 days • Putrefaction – 4-10 days • Black Putrefaction – 10-20 days • Very strong odor • Parts of flesh appear black • Gases escape and corpse collapses • Butyric Fermentation – 20-50 days • Corpse is beginning to dry out • Most of flesh is gone • Dry Decay – 50 days or more • Corpse is almost dry • Further decay is slow due to lack of moisture

24. Factors that affect Speed of Decomposition • Age • Young decompose faster than elderly • Size of body • Overweight people decompose faster than smaller people • Temperature • Naked bodies decompose faster than clothed bodies • Lower, extremely high temps preserve corpses • Lower temps prevent bacterial growth, slow decomposition • Decompose fastest – 70 to 99˚F • Environment • Bodies decompose more quickly in air (oxygen rich) • More slowly in water, or buried

25. Forensic Entomology

26. Forensic Entomology • Forensic Protocol to Collect Insect Evidence: • On Body • Above Body • Below Body • Surrounding Environment

27. Common Insects of Decomposition • Any insect containing maggot stage of life • Most common is blow fly • Tiny wasps – lay their eggs • Larvae live inside maggots as parasites • Cheese Skippers • Attracted to seeping bodily fluids • Mites and Beetles • Favor drier conditions

28. Life Cycle of Blow Fly • Egg • Three Larval Stages (aka instar) • Early and late pupal stage • Adult

30. Time of Death and Blow Fly Stage • If a corpse contains blowfly eggs the approximate time of death would be 24 hours or less. • If a corpse contains third-stage larvae, time of death is approximately 4-5 days. • If a corpse contains pupae, time of death would be approximately 18-24 days.

31. Factors that affect Insect Development • Temperature • Moisture • Wind • Time of day • Season • Exposure to elements • Variations among individual insects • Use of insects to predict time of death is only an estimate! • All environmental variations must be recorded at time of collection!!!!!

32. Accumulated Degree Hours (ADH) • Preserve some insects from the crime scene so you know exactly how old they are at the time of discovery of the body. • At the crime lab, raise some of the insects from the crime scene in the same conditions of those at the crime scene. • Record the length of time for development under the specific conditions found at the crime scene. • Compare the insects raised at the crime lab to those found at the crime scene.

33. More…. • Other forensic uses for entomology include: • If insects from another region are found, body was most likely moved

34. Summary • Manner of death refers to how the death occurred. • Cause of death refers to what led to the death • Mechanism of death refers to the specific bodily function resulting in death. • Several things can be used in determining time of death including: • Livor mortis, rigor mortis, algor mortis, stomach contents, stages of decomposition, and entomology